Top Fuel bike engine 3

[outlaw695]

Designing a V4 2500cc, OHC 4 valve engine based on the yamaha VMAX engine. Target is 1000HP @ 9500rpm!supercharged, nos, running ELF race fuel. Help me out with the right bore/stroke ratio, rod/stroke ratio, valve sizing, etc. Very interested to hear your results

 

[YvesLLewelyn]

I really don't think toluene could be called "rocket fuel".
In fact it is pretty much the opposite - which is why it was used for anti-detonation purposes in F1. As far as being toxic - it is reasonably safe to handle - far less dangerous than its cousin benzene for instance.
The 1300HP from 1.5l is a temarkable figure (- I have even seen 1500HP mentioned) from non-oxygen bearing, hydrocarbon-only fuel. The power per litre is similar to that claimed by nitro-fuelled drag cars.

 

[TrackRat]

The toluene was the primary ingredient but they were truely blending rocket fuels back in the day and they all admitted it after the 1.5L turbos were replaced with NA engines. It was very dangerous stuff they were using according to the folks in the know. Obviously the toluene has more energy than basic hydrocarbon fuels and this was the point in addition to it's anti-detonation properties for outrageous boost levels. When the engines blew they were dramatic and dangerous bombs...

 

[outlaw695]

The rule book does say "based on" very much up to the individual, Was hoping for some input on bore, stroke, valve sizing, cam etc. Power figures are easily obtainable, reliability is another thing.

The term pilot seems more fitting than rider and being a little nuts does help. The harley motors are the most common, due to the large bores needed to get the capacity it is very hard to ignite the quantity of fuel needed. Keeping in mind that nitromethane carries its own oxygen. Magneto's and twin plugs per cylinder still cant keep up.

Yes the BMW F1 engine was around the 1500HP mark, was a wild fuel that would burn you eyes while still in the drum! That was using the cast iron road car block, they found them to be best after 200,000km of use, with enough heat and compression cycles to settle the casting.

Impossible? That is what NASA said about propelling a rubber tyred vechile under the 6 second mark. Now they are in the mid 4's

Top Fuel engines are producing 1000 HP per litre, with restricted nitro content and limits on blower overdrive.

 

[TrackRat]

A ~4.25" bore seems to be reasonable for the Chrysler Hemi engines to deal with the detonation issues with nitro fuel. Naturally being a full hemisphere vs. a pentroof design things are not the same. The pentroof should be better. A longer stroke should also be better for torque. Valve sizing is based primarily on how much flow you need for the power objective. Cam duration is based on the desired peak power RPM point. Any competent, reputable cam grinder should be able to deliver a suitable cam for the application.

 

[YvesLLewelyn]

TrackRat - Do you know what the other fuel components were apart from the toluene?

 

[patprimmer]

It is no coincidence that the bore and stroke for those power levels at 9000 rpm are the same as a 5 litre SBC.

The valve size is about the same as a Honda S2000 scaled up to 4" bore with a slightly larger exhaust valve.

For cam I would copy the S2000 vtec engaged cam, add ten degrees of duration and increase lift in proportion to valve size and add another 0.75 mm of lift.

Rod length of 6" with the 3" stroke.

Regards
Pat
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[ornerynorsk]

I think the "rocket fuel" being referred to is hydrazine, not toluene, as Yyvest alluded to. Some of the guys running chizlers in the early 60's, the 392 hemi's, were playing with the stuff.

 

[drwebb]

"The toluene was the primary ingredient but they were truely blending rocket fuels back in the day . . ." -implying hydrazine??

Actually toluene releases only about 3/4 the energy on combustion (3730 kJ/mol) of basic hydrocarbon fuels like heptane (4850 kJ/mol), and much less than isooctane (5450 kJ/mol). Hydrazine is much higher still (6,300 kJ/mol), making it especially attractive when bang/pound is at a premium.

BTW, nitromethane releases a measley 709 kJ/mol, so obviously engine tuning has more to do with the final power results (as well as spectacle in a blowup) than fuel chemistry alone.

 

[TrackRat]

Hydrazine was also part of the rocket fuel... for both F1 and drag racing. <LOL> Nasty stuff!

The Nitro deal is to cram as much fuel in the engine as possible because it brings so much oxygen that you can burn more nitro than gasoline per cycle. They inject so much nitro that is why the fuel engines "drop cylinders" during a run because they flood the cylinder and twin 45 amp mags still can't always ignite the liquid/air mixture. They use something like 8 gals. of nitro in a 1/4 mile run. It's insanity.

 

[evelrod]

Speaking of "top fuel"...

http://www.ultimatecarpage.com/forum/miscellaneous/20271-top-fuel-dragster-facts.html

Once upon a time...<smile>...I watched (from a distance) a couple of "top fuel" cars simultaneously "blow" while trying for that magical "nitro/hydrazine" mix. Pretty spectacular it was for sure. I think one of the blowers went into low orbit! NHRA outlawed ALL fuel cars for several years after that one.

Oh yeah, I'm still a "rabid naysayer" about that 600hp stock block nasp. Mopar on pump gas. I'm not holding my breath. Last weekend we were pitted next to a nice little 68 Camaro with a 383 Edelbrock. Owner claimed "500hp" on pump gas. Car was nice, I'm not convinced about the 500, though. He was a second and a half slower than our 197hp@8100 Lotus...In his behalf, we are about 800 lbs. lighter...Still, weight/power just doesn't match up.

Rod

 

[YvesLLewelyn]

I am still a bit doubtful that BMW used a monopropellant like hydrazine (maybe they did I don't really know) - I think all the "exotic" and toxic fuel ingredients would have been aimed at suppressing detonation caused by the over 80psi boost used. I would think that the the boost made the 1300+HP - not explosive ingredients in the fuel.

 

[patprimmer]

drwebb

Nitromethane typically runs at about 1.6: air to fuel ratio.

709 X 9 = 6381 which is substantially higher than isooctane per unit of air consumed.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

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for site rules

 

[btrueblood]

"I am still a bit doubtful that BMW used a monopropellant like hydrazine (maybe they did I don't really know) "

Hydrazine is not just a monopropellant, but it will decompose energetically if it gets hot enough, or encounters a catalyst. Releases heat, and combustible hydrogen/ammonia species as it does so.

From recollection, nitromethane is a "monopropellant" also, in that it well decompose energetically if given enough reason to do so.

I'd always thought maybe that was one of the reasons for using it, as a sort-of "backup" ignition system.

 

[LionelHutz]

Rod

460hp is the highest power 383cu-in that Edelbrock makes and that's supposed to be a production run of 250 signature series engines with black valve covers with Vic's signature and a serial number engraved in them. The next 383cu-in is 408hp which is fuel injected with a LT1 looking intake. Edelbrock has some power packages but none of the SB ones give over 500hp either. So, he's either full of it or had an engine with some Edelbrock parts that actually was dyno'd to 500hp. That is doubtful too though since it seems that there are other manufacturer's to use if you actually want 500hp from a 383cu-in.

On another note, here's 1001hp out of a 433cu-in LSX engine.

http://www.yellowbullet.com/forum/showthread.php?t=233138

I doubt the technology you'd find in a stock block 360 the same as what that LSX engine is holding. I think the naysaying part of not believing the 600hp 360cu-in was the other post that also claimed a stock HEMI was something like 800rwhp.

 

[dicer]

So its not to OP thats designing this engine, it is Pat.

And for power density lets not forget what Fueling did with the Qaud 4, though it was turboed I think.

 

[TrackRat]

Fueling was using the Olds Turbo Quad 4 on alky just like Batten Engineering.

I think the concerns for the OP is reliability and minimal operational issues? 1000 HP from 2500 cc on nitro is not really difficult at all. Building a mechanically strong engine that will last at that power level is a bit more of a challenge.

 

[LionelHutz]

You talking Jim Feuling, right?

Get the e and u in the right place...

 

[TrackRat]

You'd think that he'd have figured out how to spell his name properly, wouldn't ya? *LOL*

 

[izzmus]

evelrod, I think that Edelbrock was, at least at one time, providing power figures for their complete "package" of componentry. 500hp sounds about right for what they claimed their Performer RPM setup provided. Assuming that he did, in fact, use the whole package, and not a lot of except-fors.

One of the vehicles I deal with maybe makes an honest 350hp. Small blower (144ci) on a mild 355, more of a street drivable noise generator than an actual all-out performance engine. The owner is advertising the vehicle for sale as making 900hp! I felt like taking our company-logo machined valve covers off of it out of embarassment.

 

[evelrod]

I think the 383 SBC in question really was the complete package. I feel that the young man really believed he had 500hp and was being truthful (as far as he was concerned).
I just doubt, based on the actual on track performance, that it was anywhere near that number.

I am truly one of the "rabid naysayers" when it comes to published hp numbers. At least by the mfgrs of the engines in question. Even the 197 of our latest 1600 is only a good talking point. I'm pretty sure I could make just about any number I needed on another dyno. I trust the 197 number only because of all the other engines that have come from this unit are pretty accurate, vis a vis, on track performance.
Still, using a dyno as a tuning tool is invaluable. Just don't get all wrapped up in big numbers.

Rod